The present invention relates to exercise equipment and more particularly, to exercise equipment that uses a variable number of weights to resist exercise motion.
Exercise weight stacks are known in the art. Generally speaking, weight plates are arranged in a stack and movably mounted on at least one guide rod. A selector rod is connected to a desired number of weight plates by a pin (or other suitable means known in the art). The selector rod and any selected weight plates are connected to a force receiving member by a cable (or other suitable means known in the art) which pulls the weight plates upward in response to exercise movement.
Although exercise weight stacks are prevalent in the exercise industry, they nonetheless suffer from certain shortcomings. For example, in order to provide a large amount of weight at a reasonable cost and within a reasonable amount of space, equipment manufacturers use a small number of relatively heavy weight plates. As a result, the amount of weight being lifted cannot be adjusted in small increments. On the other hand, a relatively large number of lighter weight plates may be used in order to provide smaller increments in weight adjustment, but the resulting equipment would be relatively more expensive and/or bulky.
Attempts have been made to address the issue of incremental weight adjustments. One such approach involves the provision of a loose half-weight (weighing one-half as much as a weight plate in the stack) that is selectively movable onto the top plate at the discretion of a user. This particular arrangement is not well suited for institutional environments because the half-weight may be lost, stolen, or misused. Another prior art approach involves the provision of a half-weight or other fractional weight(s) that is/are selectively movable from a peg on the frame onto an aligned peg on the top plate of the stack. This approach not only fails to overcome the possibility of losing the half-weight, but it creates a balance problem during movement of the selected weights, and it also increases the potential for injury due to the proximity of the two pegs and their movement relative to one another. Yet another prior art approach involves the provision of a second, smaller weight stack comprising weight plates which weigh a fraction of the weight plates in the primary stack. Unfortunately, this approach adds significantly to both the cost and the size of the equipment.
Yet another prior art weight stack machine with supplemental or secondary weights is disclosed in French Patent No. 2,613,237 to Louvet. The Louvet machine includes a stack of primary weight plates movable along a guide rod in response to exercise movement, and a stack of secondary weights movable along the guide rod and selectively stored above the stack of primary weight plates. The secondary weights are supported by gates which are rotatably mounted on rigid frame members, and which have pegs that rotate into engagement with holes in the frame members. Each of the nine secondary weights has a mass equal to one-tenth the mass of one of the primary weight plates. One disadvantage of the Louvet machine is that nothing prevents a user from releasing a secondary weight without grasping the weight. As a result, the secondary weight may be free to drop downward onto the top plate in the primary weight stack, thereby increasing the likelihood of personal injury and/or damage to the machine. Also, each of the secondary weights is not separately supported by a respective gate. As a result, the entire stack of secondary weights may be released at one time, with or without a user holding onto any of the weights.
Still other prior art approaches are disclosed in Soviet Union Patent No. 1347-948-A and Japan Patent No. 10-118222. Each of these patents discloses first and second secondary weights which are movably mounted on discrete guide rods located outside the planform of the primary weight stack. The secondary weights in the Soviet patent are pivotally mounted on respective, dedicated guide rods for movement into respective positions overlying the top plate in the primary weight stack. The secondary weights in the Japan patent are releasably secured to the top plate by a separate selector pin. A shortcoming common to both of these approaches is the need for separate guide rods for the secondary weights, and/or the imposition of non-aligned weight on the primary weight stack. In other words, despite all of the efforts discussed above, room for better solutions and/or improvements still exists.
A prior art weight stack machine having both a primary weight stack and counter-weights is disclosed in U.S. Pat. No. 4,765,611 to MacMillan (cited during prosecution of a parent application). The MacMillan patent discloses two different embodiments that use counter-weights to impose a first magnitude of gravitational force during the power stroke portion of an exercise, and that release the counter-weights to impose a relatively greater, second level of gravitational force during the return stroke portion of the exercise. One MacMillan machine places a desired number of primary weights on a first end of a lever, and intermittently links a desired number of counter-weights to an opposite, second end of the lever. The other MacMillan machine places a desired number of primary weights on a first end of a cable, and intermittently links a desired number of counter-weights to an opposite second end of the cable. These approaches are not specifically directed toward the concept of fractional adjustments to resistance, and even if they were, room for improvement would remain.
Generally speaking, the present invention relates to exercise methods and apparatus involving a stack of primary weight plates movably mounted relative to a frame, and at least one secondary weight which is selectively activated to incrementally reduce the weight of the selected primary weight plates. A connector is selectively interconnected between the secondary weight and the top plate in the primary weight stack. More specifically, the connector includes a first portion which is connected to the top plate, a second portion which selectively supports the secondary weight, and a third portion which is intermediate the first portion and the second portion, and which is connected to the machine frame. As a result of this arrangement, the secondary weight acts as a counter-weight vis-a-vis the top plate when the former is supported by the second portion of the connector. The connector is preferably a cable, and the third, intermediate portion of the connector is preferably routed about pulleys on the frame. Moreover, the frame is preferably provided with structure to guide the secondary weight in a direction opposite that of the top plate.
On some embodiments of the present invention, the secondary weight is selectively movable between an active position, supported by the connector, and an inactive position, supported by the frame. On other embodiments of the present invention, a fastener or latch is selectively movable between an active position, interconnected between the frame and the secondary weight, and an inactive position, connected at most to only of the frame and the secondary weight. In any event, the secondary weight(s) may be configured for engagement and disengagement in various ways, including rotational movement, translational movement, or a combination thereof. Many of the features, variations, and advantages of the present invention will become apparent from the more detailed description that follows.